Physical activity (PA), defined as any body movement that requires more energy than resting, has been shown to improve pain and function in persons with knee osteoarthritis (OA). Center for Disease Control and Prevention PA guidelines for adults of all ages including those with OA recommend at least 150 min/week of moderate-to-vigorous PA. However, adherence to PA guidelines is poor, particularly among persons with knee OA. Total knee replacement (TKR) is widely used to relieve pain and improve function in patients with advanced knee OA. Given the large investment in TKR and the rich evidence documenting the benefits of PA, the value of TKR could be increased substantially if TKR recipients became more physically active. In this application we propose key planning activities to design and develop the protocols for a multicenter clinical trial to address the innovative hypothesis that the period following TKR presents a window of opportunity to change fundamental attitudes and beliefs regarding PA. We hypothesize that small financial incentives coupled with regular supportive coaching will induce behavior change and facilitate adherence to PA guidelines. The planning activities include: (1) development of study protocols and regulatory materials to guide the study operations and its monitoring, (2) undertaking enrollment preparation activities to gather data on number of eligible subjects from potential centers and finalize selection of providers and centers, (3) selection of devices to objectively monitor PA to test and to select the monitor that fits the purpose of the study the best, (4) development of coaching intervention materials to standardize the intervention and test its delivery to optimize reliability, (5) development of the mechanisms, protocols, and schedules for the financial incentives intervention to optimize the timing and amount of the financial rewards for meeting PA milestones, (6) finalization of assessment tools to determine and assessment tools and monitoring protocols, and (7) creation of a data management plan to develop a standardized data capture plan and data monitoring system to optimize accuracy and minimize missing elements. Specifically, we will test the hypothesis that immediate financial rewards can offset the delay in gratification inherent in a commitment to PA and that these rewards coupled with regular support and guidance from health coaching will further increase the rate of engagement in PA and improve compliance with PA guidelines. Successful completion of these planning activities will position the research team to execute successfully a highly significant and innovative personalized intervention built on the principles of health coaching and behavioral economics.